Many modern vehicles are fitted with systems (anti-lock braking, adjustable ride height etc.) designed to improve the riding experience of the users. The riding experience could be a measure of, for example, vehicle composure or comfort. The setup of the systems of a vehicle, such that the riding experience is optimised may be dependent on the type of terrain over which the vehicle travels. Current systems have defined system configurations for a plurality of different terrain types. In a vehicle terrain response system (VTRS), such as Terrain Response (R), the user may determine the terrain type over which the vehicle is travelling, or determine the terrain type ahead of the vehicle, for example visually, and manually input this information into the VTRS which then adjusts the configuration of the systems appropriately. Alternatively, the vehicle may be fitted with sensors designed to measure certain characteristics of vehicle subsystems (such as wheel acceleration, wheel slip, steering force estimator etc.) that are indicative of the terrain type over which the vehicle is travelling. Based on these measurements, the VTRS may determine the terrain type that most likely fits with these characteristics, and adjust the configuration of the systems appropriately, for example as described in published UK patent document GB2492655. However, the determination of a terrain type by examining vehicle parameters using on-board systems is reactive to the terrain over which the vehicle is currently travelling and as such does not allow the vehicle to prepare and/or adopt an appropriate configuration in advance for the terrain over which it is about to travel, without user-input.
Our co-pending UK Patent Application No. 1402389.9 describes a vehicle control system (VCS) in which sensor output data from a plurality of vehicle-mounted sensors may be used to remotely determine the terrain type ahead of the vehicle. This is advantageous because it reduces driver workload, especially when driving off road where conditions can be demanding, and enables the vehicle systems to either automatically prepare for upcoming terrain prior to reaching it, or communicate via a human machine interface (HMI) with the driver controlling the vehicle so that they may be alerted. Such a VCS may also have benefit in automated moving devices (robots, unmanned vehicles, automatic aircraft landing systems etc.) where operator's input may not be available to prepare for the terrain ahead.
As mentioned above, different types of vehicle-mounted sensors may be used to collect sensor output data from the terrain in the vicinity of the vehicle (i.e. the terrain over which the vehicle is travelling and/or ahead of/surrounding the vehicle). The sensor output data may then be used to calculate a plurality of different parameters indicative of the terrain in the vicinity of the vehicle. Generally speaking, the greater the number of different parameters used by the VCS in determining the terrain type, the greater the probability that an accurate determination of terrain type may be made. However, the use of large numbers of different parameters in making a determination of the terrain type is computationally expensive, and therefore present techniques may resort to using a relatively small number of selected parameters only. It is therefore desirable to provide a VCS that can deal with a large number of parameters so as to maximise the probability of a more accurate determination of the terrain in the vicinity of a vehicle is made. The VTRS may then adjust other systems of the vehicle appropriately in order that the vehicle traverses the terrain in an optimal manner, or communicate the determined terrain type to the driver via the HMI.
The collected sensor output data for a particular terrain type may contain a reasonable amount of variation between readings. For example, the sensor output data for grass may vary depending on the length of the grass. The sensor output data may also contain ‘outlying’ sensor measurements: this may be caused by, for example, objects on the terrain surface. It is therefore desirable to provide a VCS for determining the terrain type in the vicinity of the vehicle that can successfully deal with sensor output data for a particular terrain type containing such variation and outlying sensor measurements in such a way that an accurate determination of the terrain type may still be made. In addition, certain parameters may show greater differences in the sensor output data between different terrain types in different situations, and it is desirable that the VCS could utilise this when determining the terrain type.
One aim of the present invention is to provide a vehicle control system that is configured to process collected sensor output data to identify certain characteristics relating to a particular terrain type and to determine an indication of the terrain type in the vicinity of the vehicle based on these identified characteristics, that addresses the difficulties described above in such a way that the systems in the prior art cannot.